1. Field of the Invention
The present invention relates to a painted, flexible, temporary decorative surface, intended in particular to be exposed in a stretched state, out of doors, such as decorations outside buildings and signs.
Such decorative surfaces in the form of large multicoloured decorations carrying information or advertising and produced on textile supports stretched vertically on scaffolding or directly on buildings are increasingly to be seen in towns. In the same way, also, giant signs or banners are produced to publicize temporary events. They are generally and often inaccurately called "painted canvases", a generic term that will be retained in the description which follows.
The production of these "painted canvases" raises two principal types of problem:
the mechanical strength of the canvases, PA1 graphical reproduction of the canvases. PA1 strong textile canvases coated with PVC (FIGS. 1A and 1B), PA1 reinforced or unreinforced strong and very lightweight fabrics, of the type of "spinnaker cloth", customarily used on racing yachts, PA1 nets of strong threads, continuously coated with a plastic film, PA1 strong textiles of the type comprising an open mesh blocked by a coating, PA1 strong, more or less open fabrics, not blocked by a coating (FIGS. 2A and 2B). PA1 the first three types of canvas have continuous surfaces that are not permeable to air, and therefore necessarily have to be very strong. PA1 The last-named two types of canvas, specifically created to reduce the effects of the wind, have a surface pierced by the multiplicity of apertures resulting from the loose weave (for example 22% of apertures in the textile shown in FIG. 2A). PA1 direct painting with a brush, PA1 silk-screen printing, PA1 painting with a manual spray-gun, PA1 application of precut elements, usually comprising sheets of adhesive-coated coloured vinyl, PA1 ink microjets applied with automatic machines, for example in four-colour printing. PA1 the first two reproduction techniques deposit relatively thick films of paint or ink, forming air-impermeable surfaces on the canvases, since the paints generally block the apertures in the canvases; PA1 painting with a conventional manual spray-gun, as well as not permitting complex reproductions to be achieved economically, projects relatively large droplets which block a large proportion of the pores of the permeable canvases; PA1 in general terms, paint or thick inks form films stretched between the fibres of the canvas; these films block the orifices and reduce the permeability of the canvas: PA1 the application of precut elements of coloured vinyl renders the canvas completely impermeable at the locations where such elements are applied; PA1 the "ink microjet" technology, using microdroplets that are automatically precision-projected, allows any apertures in the canvases to be left free, preserving their permeability to air, since the ink usable with such apparatus has to be extremely fluid, in a manner such that the microdroplets can only be deposited on the fibres of the fabric of the canvas. In this case, however, there is the disadvantage that the fidelity of reproduction is reduced since the surface area available for graphics is reduced by the surface area of the apertures in the fabric of the canvas. PA1 a substrate made from a fire-resistant, highly air-permeable, nonwoven material, PA1 a decoration produced on the substrate by automatic projection of ultrafine inks. PA1 reduction of the cost of producing support frames by virtue of reduced wind effect, PA1 reduction of the weight of the canvases (by more than 50%), PA1 reduction of the costs of purchase, transportation and installation, PA1 increase in the quality of graphical reproduction, PA1 improvement of the appearance by the elimination of gloss, PA1 improved safety, PA1 greater ease of installation.
The forces exerted by the wind and borne by the canvases increase with their surface area, their degree of impermeability to air and the level of exposure of their location. More specifically, the effects of pressure drops, may, in bad weather, transmit considerable tearing forces to the anchoring points of the canvases, situated at their periphery. Furthermore, these productions being temporary, some makers, for reasons of economy, gamble on the low probability of experiencing a storm and disregard these risks.